Todays updates cause a major problem in that you can't login because the Default theme is missing from the following location :- /usr/share/gdm/themes/Default The solution is to boot in text mode (edit the boot for the kernel that runs [latest kernel panics but that another story] and add a 3 so it looks like rhgb quiet 3 and then boot) When you are in login as root and re-crate the default folder by copying the Blucurve one and re-naming it to Default. logout and re-boot and all will be well again.